Sometime in early spring 2017, all civil IFR and VFR flight plans filed with Flight Service will be required to use the new format. Flight Service will continue to accept NAS formatted flight plans filed by the military.
Flight Service is working with vendors of the Flight Service operating systems to modify their software for exclusive use of the international format.
Formal testing of the operating systems will begin in mid-January. Upon successful completion of testing, the specific implementation date will be announced at least 30 days in advance. Detailed instructions for FAA Form 7233-4 and simplified guidance on how to complete an international flight plan are available at www.faa.gov/go/flightservice.